July, 2017 Edit:
Gym rework, raids, and legendary Pokémon have breathed new life into the game. Niantic still needs to work on heavy resource drain causing phone to overheat, gym battles to glitch, and frequent app crashes.
Original:
Very fun and a great way to get out and explore your neighborhood and city. Servers have had major issues, inconsistent stability, and the game is loaded with bugs, though.
Hoping they get it fixed soon and add new features and game modes to give the game more long term playability.
Terryc85 about Pokémon GO, v1.39.0